Custom productivity tools for ArcGIS CityEngine using the Python API

When working with ArcGIS CityEngine scenes, most editing tasks are simple, but some can become tedious when repeated across many shapes or street segments. Typical examples include changing attributes across shapes with different rule files, reorganizing street lanes or cleaning up street networks.

We created the Python Scene Editing Tools to simplify such time-consuming and repetitive edits. Using these tools, power users can edit scenes more efficiently.

But there is more to the tools than solving these particular editing problems. They also show how CityEngine can be extended with custom editing capabilities built on its Python 3 API and modern web technologies.

In this blog post, we cover the key features of the tools, how to get started and a few step-by-step examples.

Tools

The tools are grouped into five categories, each focused on common editing tasks.

• Attribute Editing: Set attributes on all selected shapes regardless of their rule files, list all attributes, read attribute values
• ESRI.lib Street Lane Rules: Configure crossings, vehicles and vegetation
• Street Configurations: Detect segments with no configuration assigned, list configuration names
• Street Lane Editing: Split, merge and resize lanes, create multiple lanes by numbers, get street and lane widths
• Street Segment Editing: Merge segments, detect and merge consecutive segments, straighten consecutive segments, get and set segment lengths

Getting started

The tools are installed and launched entirely from within CityEngine. Before you start, make sure CityEngine 2026.1 is open.

1. Install: Download the example project through Help → Download Tutorials and Examples → Example Python 04 Scene Editing Tools 2026.1.
2. Run: In the CityEngine Navigator, open /Example_Python_04_Scene_Editing_Tools__2026_1/scripts/main.py and run it with F9 or Python → Run Script.
3. Use: The tools open in a new window with a web-based interface and in-app documentation for each tool. We recommend placing the window with the tools next to CityEngine. The tools apply to the scene that is currently open in CityEngine.

Examples

The following examples show how you can use the tools for various editing tasks.

Example 1: Attribute Editing

The CityEngine Inspector lets you edit rule attributes of several shapes at once only if they share the same rule file. The Set Attribute tools let you set a value on all selected shapes, regardless of their rule file.

Open /Example_Python_04_Scene_Editing_Tools__2026_1/scenes/Set_Attribute.cej in the Navigator. Our goal is to adjust the orientation and position of residential houses generated from different rule files.

1. Select all shapes in the Blocks layer.
2. In the tools window, expand Attribute Editing and open Set Attribute (String).
3. Enter /ce/rule/Direction as path and Parallel to Left as value, then click Run.
4. Open Set Attribute (Float). Enter /ce/rule/Offset as path and 10 as value, then click Run.
5. All blocks now use the new direction and offset.

Example 2: ESRI.lib Street Lane Rules

In the CityEngine Inspector, crossings must be configured manually lane by lane. The Set Crossing tool lets you switch crossings on or off for all selected segments and nodes at once.

Open /Example_Python_04_Scene_Editing_Tools__2026_1/scenes/Set_Crossing.cej in the Navigator. Our goal is to remove the crossings in the bend of the side street and the double crossing at the bus stop.

1. Select the diagonal segment of the side street and the node where it bends.
2. In the tools window, expand ESRI.lib Street Lane Rules and open Set Crossing.
3. Set start and end to Disabled, then click Run.
4. The crossings at the bend are gone.
5. Select the short segment of the side street and the main street segment left of the intersection.
6. Open Set Crossing again. Set start to Disabled and end to Enabled, then click Run.
7. The crossings in the bend and the double crossing at the bus stop are gone.

Example 3: Street Lane Editing

The Street Lane Editing tools let you create, resize, split and merge the lanes of a street configuration efficiently.

Open /Example_Python_04_Scene_Editing_Tools__2026_1/scenes/Street_Lane_Editing.cej in the Navigator. Our goal is to redesign a short street segment to accommodate a bus stop. This involves extensive rearrangement of the lanes.

1. In the middle segment, select the four roadbed lanes south of the median.
2. In the tools window, expand Street Lane Editing and open Merge Lanes.
3. In Merge Lanes, click Run.
4. The four lanes are now a single 8.6 m lane.
5. Open Split Lane by Widths, enter [3.3, -1, 2.5] as widths (-1 takes the remaining width), then click Run.
6. The segment now has lanes of 3.3 m, 2.8 m and 2.5 m.
7. Repeat steps 1–5 for the lanes north of the median, using [2.5, -1, 3.3] as widths.
8. Assign and configure ESRI.lib lane rules on the new lanes. Here, we use Bus_Lane.cga with yellow asphalt and Bulb_Lane.cga.

Example 4: Street Segment Editing

The Street Segment Editing tools let you select, straighten and merge chains of consecutive street segments efficiently.

Open /Example_Python_04_Scene_Editing_Tools__2026_1/scenes/Street_Segment_Editing.cej in the Navigator. Our goal is to clean up the messy segments in the middle of the street.

1. Select the middle segment of the street.
2. In the tools window, expand Street Segment Editing and open Select Street Segment Chain.
3. In Select Street Segment Chain, click Run.
4. The tool selects all five segments between the intersections.
5. Open Straighten Street Segments, then click Run.
6. All nodes now lie on a straight line.
7. Open Merge Street Segments, then click Run.
8. The street is now one segment from intersection to intersection.

Conclusion and next steps

In this blog post, we introduced the Python Scene Editing Tools for CityEngine and showed how they speed up tedious and repetitive scene editing tasks. To try them yourself, follow the installation steps in the Getting started section above. You can also use the CityEngine Python 3 API and web technologies to create your own custom tools.